Don't you just hate it when that drop-dead gorgeous 65/66 Mustang of yours won't start? Or when you turn on the radio and the turn signals start flashing? If you have any questions that you think I might be able to help you with, or, if I have posted something that still doesn't seem to be as clear as it could be, please feel free to ask.

Hello

There is a very large class of people that own 65/66 Mustangs that, as far as I can tell, anyway, have been, for the most part, ignored entirely. They don't really want that 100 pt. show car that is so nice and was soooo expensive that they're afraid to drive it, they also don't want to make their car capable of achieving warp factor three. They just want this car that they dearly love to be able to cruise around smoothly and reliably, without having it dump them out on the side of the road or have it start making weird noises or belching out big clouds of funky-smelling smoke. And I think, truth be told, that this is by far the largest class of Mustang owners. They take their car to some technician when what they actually need is a mechanic, and this, frequently, does not work out very well at all for the owner. They don't want to re-engineer the entire car, they just want someone to fix what broke. These are the people that I am trying help out with this blog. Some problems require a little bit of back and forth, as in, "Try this." "I tried that and it didn't change anything."" Oh. well, you probably need to try that." " I tried that and it helped, but it still isn't quite right." "Now you need to try this...." If you go to http://www.allfordmustangs.com/ and then go to the classics forums, you will be able to do that with a pretty hefty gathering of some very knowledgeable people that also happen to be very friendly. None of that ridiculous one-upmanship, no flaming or abuse, none of that stuff. Just good, solid advice from people that know what they are talking about.

Monday, November 23, 2009

Finding an electrical draw

If you find that your car's battery dies in a day or two when you don't drive the car, it could be that you have an electrical draw somewhere that is draining the battery. First, you would want to find out if this is actually what's happening. Start by charging the battery, and, with the positive battery cable connected and the negative battery cable disconnected, and take a volt meter and connect the positive probe of the volt meter to the negative battery cable and hook the negative probe of the volt meter to the negative battery post. With the doors of the car closed and the key in the 'off' position, the volt meter should read zero like that. If it it does indeed show zero like that, then you do not have a draw, and the problem is going to be the battery itself. If the meter does show voltage like that, something is pulling power when it's not supposed to. Fortunately, the list of suspects on a 65/66 Mustang is very short. You have the horns, the headlight switch, the emergency flasher/ cigarette lighter circuit, the ignition switch, and, if you have a convertible with a power top, the top switch. Also, the charging system has a wire that feeds into the hot side of the starter solenoid, so that, when the car is running, everything electrical is running off of the alternator/ generator instead of the battery, and, the ammeter gauge/ charge indicator light has a wire attached to this same post on the starter solenoid.

None of this stuff is on a fuse in the fuse box, except for the emergency flashers, so, don't start pulling fuses one at a time and checking to see if the draw went away. Unless the problem is with the emergency flashers/ cigarette lighter circuit, which it almost never is, the problem won't go away like that. Start by unplugging the alternator harness from the headlight harness and see if the draw went away. It's the three-prong connector down near the frame rail, kind of underneath where the battery is. If the draw went away, plug that back in and unplug the connector from the side of the voltage regulator. If the draw reappears, the problem is the alternator. Check and see if the black wire with the yellow stripe attached to the 'bat' post on the back of the alternator is shorting itself out on the alternator case somehow and, if yes, fix that. If it isn't, then you need a new alternator. If the draw does not reappear with the alternator harness plugged in and the voltage regulator unplugged, you need a new voltage regulator.

If the draw is still there when you unplug the alternator harness, then the problem is with one of the other systems mentioned, and, you will probably need to remove the instrument cluster to have a look back there. If you look in the april of 08 section here, there's a post on how to do that. It isn't difficult at all. Before you do that, though, go ahead and pull the emergency flasher fuse and see if the draw goes away. If no, go ahead and snatch the instrument cluster out. If yes, put the fuse back in and unplug the wire from the back of the cigarette lighter and see if the draw goes away. If yes, replace the lighter.

Once you have the instrument cluster out, disconnect the headlight switch connector from the headlight switch and check to see if the draw went away. If no, the problem is not with the lights or the horns, since the horn circuit gets it's power from the headlight switch. That leaves the ignition switch. You can check the wire that is hooked to the + or 'bat' post on the coil with the volt meter to see if it shows power with the key in the off position, but, if it does, you need to replace the ignition switch and you have to remove the instrument cluster to do that, so, it wasn't needless work removing the instrument cluster.

If the problem went away when you unplugged the headlight switch connector, plug the connector back in, and unplug the turn signal switch at the base of the steering column. If the draw goes away, the problem is something in the turn signal switch, most likely the horns. If the draw does not go away, unplug the connector behind the dash, kind of up above the fuse box , that the taillight harness plugs into. If the draw does not go away, the problem pretty has to be up front with the headlights or front parking lights/ turn signal lights. It isn't complicated, it's just a question of picking a place to start and working your way through until you find the problem. You don't want to fall into the trap that ensnares many, which is assuming that the problem is with component A and replacing it, only to discover that the problem is still there, so you then replace component B, C, D, etc... Don't start just throwing new parts at the car until the problem disappears. Take a minute to figure out what's actually wrong, and then fix that. You'll be much happier with this way of doing things in the long run.

I have a problem with my '67 convertible top. It worked fine when I put it into the garage last November. Over the Winter, I painted the engine compartment, inner fenders, engine block (without removing the engine). In doing so, I did remove the solenoid, but thought I put it back correctly.Now, the top doesn't work. I checked the unit behind the rear seat. It seems that it's getting NO power. I read somewhere that the "top" gets its power directly from the solenoid. But I'm unable to trace that wiring. From what I see, the solenoid has a ground strap, a line to the "+" battery terminal, wires to the alternator harness, and wires to the front-right headlite. I see no wires going to the engine compartment firewall, to feed the "top" switch in the instrument cluster (I've never messed around with the instrument cluster).Can you suggest any leads I should pursue? thanks alot...Joe

There should a wire going from the switch on the dash going through the firewall, and attaching to the same post on the starter solenoid that the positive battery cable is attached to. It will have either a circuit breaker or a fuseable link and a junction block near the starter solenoid. I would start at the switch, find the wire that's heading towards the front of the car, and track it down to see where the other end of it is.

Hello Veronica..I located the wire coming thru the fire wall, traced it, reconnected it to the solenoid, and the Top now works. Thanks!

Separate question: Upon trying to start the car a few weeks ago, the engine entered into a sort of intermediate state. The only way I can explain it is that the engine was half on, half off. Rumbling in the weirdest way, I thought it may blow up! I quickly turned the key to shut off the engine, but there was no effect on the engine. It continued to rumble in the worst way. I proceeded to disconnect the battery cable, and the engine finally died.Now, when I attempt to reconnect the positive battery cable, a huge arcing spark occurs. My dad (a retired mechanic) suspects that the Starter went bad. What do you think?

What your dad suggested would be a legitimate possibility on a GM vehicle, but, the way the Fords are put together, that wouldn't be the case. On your car, there is only one wire going to the starter, that being the one from the backside of the starter solenoid. For the starter to do anything, there must be a power supply coming through that starter cable. For that to happen, it must be some other component that has failed. The one component that you know for sure is functioning correctly is the starter. It gets power, it starts cranking, just like it's supposed to. Disconnect the starter cable from the starter solenoid and then reconnect the battery and check with a volt meter to see if the post that the starter cable attaches to is showing power. If yes, disconnect the two small wires from the front of the solenoid and check the post again for power. If yes, you need a new starter solenoid. If no, check the red wire with the blue stripe that attaches to the post marked 'S' on the front of the starter solenoid to see if it shows power with the key in the off on position. If yes, either that wire is shorting itself out on some other wire that has power or, you need a new ignition switch. If no, it is possible that you had those two small wires switched around. That would make the car do what you describe, and, it is a very, very easy mistake to make. Let me know what you figure out.

On re-reading what I said, it appears that I failed to say that, when you disconnect the starter cable from the starter solenoid, also unplug those two small wires from the front of the starter solenoid. Then, if th post that starter cable attaches to shows power, you need a new starter solenoid.

OK..I disconnected the starter cable from the solenoid, disconnected the two wires from the front of the solenoid (which, by the way, were connected correctly, with the red wire w/ the blue stripe connected to the post labeled "S"), and finally reconnected the positive battery cable. I checked for power on the post that the starter cable attaches to..negative lead of the voltmeter on the negative post of the battery,,,and, NO POWER. So I guess the starter solenoid is good. Then I checked the red wire with the blue stripe that's connected to the "S" post on the solenoid for power, with the key in the off position, and...NO POWER. As I stated above, the two wires connected to the front of the solenoid are not mixed up; the red one with the blue stripe goes to the solenoid post marked "S".Not sure what to check next.One thing, FYI... - there's a junction "stand-off" located just below and to the left of the solenoid on the inner fender that broke last winter. The union joins two wires; ...one wire from the right side of the solenoid, and one one the comes from the direction of the front-right headlight and under the battery tray. The stand-off broke last winter while painting, and now I simply have the "union" floating in the air,,,,but I can't see how this can affect anything.Anyway, I'm going to keep looking and checking things, and certainly appreciate your kind suggestions...

hey Veronica..I want to update you with what happened today..As you see from my 8/25 post, I was at a dead-end. This morning, I said to myself,,"let me reconnect the positive line to the battery terminal"; when I had tried this last time, I was met with a big spark, that left a notch in the positive battery terminal. So I tried it again this morning, FIRST time since BEFORE i disconnected the Starter cable and Solenoid wires (per your suggestion) last week...No Spark. good. Then I turned the key, and the engine started right up. Go figure. I drove the car around, shut it off, turned it back on, etc,,, No problem. This afternoon, I took my 15 and 10 year old daughters shopping for school supplies. We left the store, back to the car, and I turned the key....Just like before, the car entered into a half-on / half-off mode, rumbling,,,with the Starter going full blast. I turned the key off, but that had no effect. I pulled off the primary distributor wire, ,,no effect. I pried off the positve line to the battery (I purposely did not fasten it tightly this morning), and the engine finally died.

Well, I had to try starting the car and get us home. I hit the positve battery line against the positve battery terminal,,,Big Spark!...and again, Big Spark!,,,putting more notches/gouges in the terminal head. I can't get this thing on. What to do?I thought to myself, the only thing I did to the car since last time, was I disconnected the Starter Cable and Solenoid wires. By doing so, am I resetting the Solenoid somehow? After all, the Solenoid is a sort of switch,,right?There I was in the WalMart parking lot, hood up, kids in the back seat, with my wife on the way to pick us up, or, at least, them...I went back into Walmart, purchased a cheap mini - adjustable wrench ($1.99), and back to the car. My wife had shown up at this point.I removed the Starter cable from the Solenoid, pulled out the two wires from the front of the Solenoid, ,,waited a few seconds, and put it all back on. Then I reached for the positve battery line, and hit it against the Postive battery terminal. No Spark! I fastend the line to the terminal, turned the key, and the engine turned on beautifully. I drove home, the kids drove home in the Pacifica.So, my reasoning is, the Solenoid is faulty. A relay switch inside tends to stick, but not always (recall, I turned the car on/off repeatedly this morning). When I tested the Solenoid last week (per your directions), it proved good. Because it was! By then, the relay had already reset itself.I plan to replace the Solenoid (funny, just last year, I replaced the original Solenoid with a new one that I bought on line, likely a cheap one, not that there was anything wrong with the original part, ,,I was just updating many engine components with new ones).OK..just thought you would like to hear this...thanks...!

Hi Joe. Cool. That certainly sounds like the solenoid's hanging up on you. The only other possibility would be an intermittant problem with the ignition switch itself, but, that would not be very likely. I've always been pretty happy with the BWD Select S63 starter solenoids. Most major auto parts chain stores carry them. It sounds like that should have you up and running. I'm glad to here that you got it all sorted out.

Hi Veronica.I read through the finding an electical draw post and followed all of the steps that you listed out and I am still getting a draw of between 12.3 and 12.5 volts no matter what I unplug. I tried disconnecting all of the wires from the left side of the starter solenoid (one connection goes into the car, one goes to the alternator, and one goes to the voltage regulator) except for the positive battery cable and the voltage draw goes down to around 6 volts. Could this mean there is a problem with my solenoid or starter?

Interesting. Assuming that we are talking about a 65/66 model car,disconnect everything from the starter solenoid except the positive battery cable and the starter cable, including the wires on the 'S' and the 'I' posts on the front, have both battery cables hooked up to the battery, take the positive probe of your volt meter and hook it to the post of the solenoid that the starter cable is attached and the negative probe to the negative battery post. Repeat that for the 'S' and the 'I' posts of the solenoid and see what you get. If any of those show power, it's the solenoid.

Verinca,Yeah I have an early 65 Coupe. (Built in August of 64)I got no voltage when testing the solenoid like you suggested. So I assume the solenoid is good. If I leave the starter cable hooked up, the "S" and "I" wires hokked up, and the positive battery cable attached I get a reading of 6.13 volts consistantly when I have the negative probe of the volt meter on the negative battery terminal, and the positive probe on the negative battery cable. If I attach either the atlernator connection (black with a yellow stripe) or the connection that goes to the voltage regualtor/firewall (yellow wire and black wire with yellow stripe) then the voltage jumps to 12.5 volts. 90% of the wiring in the car is new (installed last august) and so is the starter and alternator. The voltage regulator is probably 5 years old. Any other ideas? My name is Steve by the way.

Another thing I just found that I thought was interesting is that when I leave both battery cables disconnected and place the negative probe on the negative terminal and the positive probe on the negative battery cable I get a voltage of 6.1 as well. That can't be just coincidence. Thanks for you help!

Cool. Nice to meet you, Steve. You wouldn't happen to be from Cleveland, would you? If yes, the tribe is looking pretty good so far.

What you are describing sounds very much like an alternator with a diode that has figured out a way to short itself out on the casing of the alternator somehow. And, yes, it is possible for one to do that and still test out like it's ok. Try unhooking all of the wires from the back of the alternator, unplug the connector from the voltage regulator and have everything else hooked up like it's supposed to be and see if the draw is still there.

I'm actually from Denver, I have had the tribewahoo email address forever, I was a big time Indians fan in the 90's. I've pretty much given up on rooting for anyone except the Rockies now.

I tired disconnecting all of the wires from the back of the alternator and unplugging that connection between the alernator harness and the voltage regulator harness and with everything else connected like normal its stil 12.48 volts. If I take that connection that has the yellow wire that goes to the voltage regualtor and the black/yellow stripe wire that goes to the firewall off of the starting solenoid then it drops to right around 5 volts. I tried disconnecting the voltage regulator completely again and it made no difference. I also looked at the wiring diagram at where that black/yellow stripe wire goes into the firewall and it goes to the cigarette lighter fuse and a yellow wire splits off of that and goes to the ignition switch so I tried taking out the ignition switch again and that made no difference and I treid taking out the fuse for the cigarette lighter and it made no difference either. The other thing I did was check and make sure that where the negative battery cable connects to the engine block was clean and making a solid metal to metal connection and also the ground on the back of the block to the firewall, I made sure that was clean and a solid connection and also that the voltage regulator was a clean ground as well and they all are. This really has me stumped, but I'm not an expert when it comes to the electrical system.

That black wire with the yellow stripe actually goes three places after it goes through the firewall. It does indeed take power to the ignition switch and the emergency flasher/ cigarette lighter circuit, but, it also supplies power to the headlight switch.

It appears that you might possibly have more than one draw. The thing to do would be to back up and start from scratch on this one. First, with everything hooked up, unplug the headlight harness from the firewall and see what sort of a draw you have, if any. If you have no draw after that, your problem is behind the dash. If the draw seems to be cut in half, one of the problems is behind the dash and the other is under the hood. If that changes nothing, the problems are all under the hood.

If the problems are all under the dash, unplug the connector from the back of the ignition switch, unplug the headlight switch, and pull the fuse on the emergency flasher/ cigarette lighter circuit. If the draw is still there, the problem is somewhere along the length of the black/yellow wire, or along one of the three wires that split off from that black/yellow wire. If the draw is gone, plug the headlight switch back in and check for the draw. If no, connect the ignition switch back up. If no, put the fuse back in the cigarette lighter circuit. This will tell you which system is having the problem(s)

If there is one problem under the dash and the other under the hood, do what I just said to find the one under the dash and fix that, then unhook everything from the starter solenoid, except for the positive battery cable, unplug the voltage regulator and disconnect all of the wires from the back of the alternator. Unplug everything until you have no draw at all, then start reconnecting stuff until the draw reappears, starting with that black/yellow wire that hooks to the starter solenoid. That should put you on track. Let me know how that goes.

Hi Veronica, I started everythhing again from scratch and found 2 things that I think were the problem. One of the them was that my glove box light switch was bad and the other seems to be the voltage regulator. Once I get a new voltage regulator I will test to make sure and let you know. As for the golve box light switch, I'm just going to leave it unhooked and tape off the connection on the wiring harness so that nothing shorts out, I figure that light is unneccessary anyway.

Got the new votage regulator and have everything putback together and I'm not measuing any draw so I'm down to the ultimate test, leave the battery hooked up and see if its dead tomorrow... Thank you for all of your help! Now I'm on to the next project, replacing the heater core and defroster pleanum.

Cool. I'm glad to hear that you got it all sorted out. Heater cores are pretty easy on the 65/66 cars. You can remove the heater box from the car without having to remove the entire dash assembly, like on a 69 and up.

Yeah, I have everything all taken apart, just waiting on the new heater core, gaskets, and defroster pleanum to get here from mustangs unlimited. When I started on this electrical mess, I noticed some coolant dripping in onto my passenger floor mat and found it coming from the heater box so when I found got to a snag with the electrical I took the heater box apart and found my problem there. Thanks again for all of your help, I will definitely keep my eye on your blog to see what new tech tips you post!

I have a 65 mustang. after testing my vehicle I found a draw of -0.20. I went through all the steps you recommend. Disconnecting headlight switch, turn signals, ignition switch, three wires from alternator, voltage regulator,and cigarette fuse. I changed the starter and I still have the draw. I tested the solonoid and it appears to be good.

On a another note for some reason the positive cable to the battery gets very hot when i drive the vehicle. A few days ago I drove the vehicle for about ten blocks and when I turned off the car it wouldnt start again. Battery was completely dead and positive cable was extreamly hot. The alternator is holding charge. Upon testing at idle it gaive 13.4 and without idle 12.5.

Hi, Louis. On the draw, I think that I would start by hooking everything back up, and then disconnecting everything from the starter solenoid except for the positive battery cable and see what that did to the draw. What sort of radio do you have in the car?

On the other thing, was the cable hot after having attempted to start the car with low voltage? If yes, having it heat up under those conditions is normal. I would suspect the condition of the battery. If the alternator is functioning correctly, which it sounds like it is, and the battery is discharging itself and not holding the charge, that would definitely indicate that the battery might possibly be bad.

I don't know if you're still out there, but I just installed a new steering wheel kit. When I push the horn button, the power to the car dies! When I take the wheel off and operate the horn, its fine. Any ideas?

Hi, Randy. Yup, I'm still here. That would just about have to be a short in the wheel on the contact point that is not hot unless the horn button is pushed. What type of steering wheel are we talking about?

Hi Veronica. Thanks so much for your blog and all of the great info. Sorry in advance if this is too long.

Ive got a 1965 ford falcon futura convertable, 289. Not a show car but a dialy driver. I recently replaced the water pump, battery, thermostat, alternator, alternator wiring, and upgraded to a flamethrower style ignition system coil and electronic points. Car runs great but I have a battery drain so that when I leave it overnight the battery is dead.

After several weeks of forum searching and working on the problem I have narrowed it down to a drain coming from my voltage regulator or its wiring. When I connect my DVM (As you suggested neg to neg and pos to neg batt line) I get a 12 volt reading. If I disconnect the voltage regulator cable from the starter solenoid and perfrom the same test, I get a normal DVM reading of less then.04. So I replaced the voltage regulator and have the same readings and battery drain. If I unplug the voltage regulator I have the same drain. So i'm at a loss.

I looked for any obvious wiring defects on the voltage regulator feed and didnt find any. I considered picking up a one wire voltage regulator from falcon parts in an effort to bypass the potentially faulty voltage regulator wiring.

Hi, John. No need for any apology. Too long is a lot better than too short when it comes to describing electrical weirdness. I would start with unplugging the voltage regulator and checking the terminals on the connector that plugs into the voltage regulator to see if I got a reading of significant power on one of those terminals. If yes, you have probably purchased a defective alternator. If that seems to be the case, I would then disconnect the black/yellow wire that goes from the alternator 'bat' post to the hot side of the starter solenoid, and then check from the disconnected negative battery cable to the negative battery post for the draw. If no to that, it's probably the alternator.

If no to a power reading at the connector for the voltage regulator with everything else hooked up. you probably have a bad voltage regulator. Sadly, there is nothing strange about new parts being D.O.A. these days. Hope that helps, and let me know what you find out.

I've always had a soft spot in my heart for the early and mid sixties Falcons. Those were much better cars than people give them credit for, and, prior to the 65 Mustang, the 60 Falcon was Ford's single year best selling car ever.

Hi Vernonica,Thanks for your response. I did what you recommended on your blog and checked every plug in the dash. I finally found that if I unhook my blower switch the power drain goes away. So I figure that either the switch or the Heater blower motor is bad. I might just replace both to be sure.

The problem is almost certainly not with the blower moror itself. There two possible configurations for the heater blower wiring on your car. One will be with a blower motor with three wires coming out of it and no resistor on the front of the heater box, and the other will be with two wires coming out of the blower motor and a resistor on the front of the heater box.If you have the first type, the problem would probably be with the switch. How that one works is power comes from the fuse box to the switch and from there goes on to the blower motor, with that third wire being the ground for that system.

If you have the resistor type, that system works backwards from the first system. Power goes to the blower motor, and from there, through the resistor and then to switch, which works as a path to ground on the dash. On this, if you have a short in the wiring anywhere between the power source and the switch, that would cause a draw.

Vernoica, wow you are good. You were right again -- it had nothing to do with the heating system. I was wrong so I broke down and took the car into an auto electrican who in 15 minuets figured out the stereo shop had crosswired the stereo with multiple hot lines. Thanks for all your help and finally its fixed.

This site has helped with many of my past problems but I am really stumped. I have a 1966 and have gone through three starter solenoids in the last month. I assumed that the cheap models were the root of the problem so I purchased more expensive versions but these also failed. Reading your earlier posts I wondered if there was an electrical draw that was draining my battery and then the low voltage "welded" the solenoid. In short, I followed your suggestions outlined on April 15 2011 at 426. I removed the negative battery cable and placed my voltmeter probes between the negative cable and the negative post (with everything else hooked up as normal) and it read a 6 volt draw. I removed the headlights wiring harness at the firewall, alternator harness, voltage regulator connection, the other harness that also plugs into the firewall (main disconnect?), and then finally all the lines feeding into the left side of the solenoid. Draw never dropped off. I removed the wires connected to the I and S posts as well as the starter cable. Still a draw! So as a last result, I removed the positive cable from the solenoid (left it hanging there without touching anything) and the draw remains?!?! Why is there a draw on the negative ground when the positive cable is not connected to anything? Thanks for your insights.....

That is interesting. I think that I would start by hooking everything back up, unplug the alternator harness, disconnect the alternator ground down there were the negative battery cable is attached to the engine block, and see if I had a draw like that. If no, it's time for a new alternator and regulator. And, yes, the low voltage will kill a starter solenoid in a hurry.

Hi Veronica, you were right again. But I had to completely disconnect the alternator (remove the whole thing) to get the draw to disappear. Maybe an internal diode was fried and drawing power? Anyway, it is out and I have purchased a new alternator as well as the new alternator harness, I mean, why not, right? However, I noticed that the new harness is slightly different than the current one. The new harness has a black and yellow wire (battery I assume), white (field), black and red (ground) but no STA wire and I am not sure what that line does anyway... ALSO, the current setup has a thick wire going from the BAT post on the alternator directly to the left side of the starter solenoid. Isn't this second wire redundant as the black and yellow wire quick connects to the headlight harness and attaches to the left side of the solenoid anyway? Thanks in advance, Paul.

I'm glad to here that you got the draw issue sorted out. Your car, being a 66 with gauges, would not use the stator post on the back of the alternator. The stator post was used for the cars that came with a charge indicator (idiot) light instead of an ammeter gauge. The seemimgly redundant black wire with the yellow stripe is actally a continuation of the one that joins the headlight harness. The one in the headlight harness takes power from the hot side of the starter solenoid to the interior of the car, where it splits into three wires behind the dash. One of them is yellow and takes power to the ignition switch, one stays black/yellow and takes power to the emergency flasher/cigarette lighter circuit of the fuse box, and the third is black with sort of a purple-looking stripe which takes power to the headlight switch. The black/yellow wire that goes from the 'bat' post on the back of the alternator to the hot side of the starter solenoid is for power to get from the alternator to that wire that takes power to all of that stuff behind the dash. All that your battery is supposed to do is start the car. After the car starts, everything is running off of power from the alternator, which is also supposed to charge the battery so that the car will also start the next time you ask it to. If the car is running off of power from the battery, that means that something has gone seriously wrong with the charging system.

As far as the cause of your draw goes, you are probably coreect in supposing that a diode has gone bad. When one of them fries and finds a way to short itself out, it will show like a draw. There are things inside the alternator that are magnetic. A brutally oversimplified explanation of electricity and magnetism is that they are actually the same thing which displays different characteristics when viewed from different frames of reference.Thank you, Albert Einstein. But, magnetic fields can cause electrical current to flow in certain circumstances, which is what makes an alternator or a generator work in the first place. That is what your volt meter was probably picking up.

Veronica, me again... finished installing the alternator, new harness, new voltage regulator and everything is working great. Battery has 12.3 volts and jumps to around 15 volts when the car is running. I drove it to work and back today and noticed that the battery is leaking acid. It looks like acid is bubbling up from the battery plug covers that can be used to fill the battery if needed. Not sure why the battery is boiling over. Bad battery (it is just a few months old), bad voltage regulator, something else? What do you suggest or where to start troubleshooting it. Thanks in advance, Paul.

Hi, Paul. It sounds like your battery is being overcharged, and, that is almost always a defective regulator. If the voltage jumps up to like 14.7V, that is about right, but, it isn't spposed to hit that level until somewhere above 2000RPMs. If it's doing that at below something in the 1500 RPM range, the battery is definitely going be overcharged. I would hook a volt meter to the battery, start the car, and then slowly increase the RPMs and see what volyage I was getting in increments of a couple of hundred RPMs. You should have something slightly above 12V at idle and a steady progression upward topping out below 15V at like 2200 RPMs if you have a standard sized pulley on the alternator.

Veronica, definitely overcharging. Before starting I get 12.5 volts, at idle I get 14.4 and it only reaches 14.5 after after revving up from idle to 2200 rpms. Probably an error on my part but I didn't measure the pulley wheels between my old and new alternator. They looked the same to my eye but I should have put a tape measure on it to confirm. I have already returned it and didn't pull the old pulley wheel so it is gone by now. If not the pulley then maybe the voltage regulator? new from NPD but that doesn't mean that it is bad. Other suggestions?Thanks as always, Paul.

With the readings that you got, that is almost certainly a defective voltage regulator. If the pulley that you had looked about right, that was close enough. The K code cars came with a much larger alternator pully in order to reduce the number of RPMs the alternator turned relative to the motor RPMs because Ford knew that the K code cars were going to be run at much higher RPMs.

Veronica, I agree, 14.5 volts at idle made me think it was the voltage regulator as well. With the battery spewing acid all over the driveway, the starter beginning to fail, and the VR not regulating, I decided to replace all three yesterday. Purchased an Optima red top, new starter and BMW VR. Remember I just installed a new VR and a new alternator a few weeks ago. Once they are all hooked up I am still getting 14.5 volts at idle as well as when revving up above 2000 rpms. I am afraid I will overcharge the new battery.

Wondering if I connected VR incorrectly? I have the part mounted in the normal spot and the four pins are facing up (pin labels from back to front are F S A I). The new harness has the field wire (white) wire on the F pin, light green with red stripe on the S pin and yellow line on the A pin (with that extra yellow plug for the radio suppression which I have nothing connected to). The last I pin has no wire in the harness that connects to it. I also connected the ground coming off the VR harness to one of the screws holding the VR onto the sidewall. Anything jumping out at you as not wired or mounted correctly? Thanks in advance, Paul.

t sounds like you have everything hooked up correctly. You should be getting less than 13V at idle. A pulley on the alternator with a larger diameter would lower the RPMs of the alternator, but, you shouldn't need that. The one you are talking about from NPD with a diameter of something in the 3 7/8 range is a reproduction of what was used by Ford on the K codes to prevent what is happening to you. I would first try dropping the idle down as low as it will go and still keep the motor running and see what kind of readings I got like that. If that seems to straighten the issue out, I would go with the bigger pulley, even though it sounds like you have purchased a defective voltage regulator. I don't know how much you enjoy returning things and belly-aching about the shoddy workmanship that went into this raggedy son of a gun, but, you might have to make a few trips to get one that actually works correctly. Personally, I will make as many trips as I need to, purely on principle, but, that's just me. The problem with the voltage regulators is usually that they aren't adjusted correctly when they leave the factory. I'll post something on how to adjust them